JPS62157049A - Photosensitive body for positive charge - Google Patents

Abstract

PURPOSE:To obtain the titled body having an improved printing resistance by providing a protective layer contg. an electron acceptor and an electron donor as a substance capable of contributing to transferring an electrostatic charge carrier, and by incorporating a resin curable by light or heat to a binder of the protective layer as a main component, thereby controlling a harmful outside action of influences of a light radiation, a corona discharge and a humidity, etc., and especially a mechanical abrasion and a damage. CONSTITUTION:The protective layer contg. the electron acceptor and the electron donor is formed on the photosensitive layer composed of a monolayer or a laminated layer. The protective layer having an improved mechanical strength against the surface of the titled body and the improved printing resistance is obtd. by using a thermosetting resin to the binder of the protective layer. As the electron acceptor usable to the protective layer of the photosensitive body, one may use citric anhydride, maleic anhydride, dibromomaleic anhydride and phthalic anhydride, etc. As the electron acceptor suitable to forming a CT complex with the electron donor, the compd. having a large electron affinity EA is preferably used, and the compd. of 0.3eV<=EA<=1.8eV is preferably used. The amount of the electron acceptor contd. in the protective layer is 0.1-50wt% on the weight basis of the titled body.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to improvements in positively charging photoreceptors.

[Conventional technology]

Conventionally, for example, as an electrophotographic photoreceptor, a photoreceptor having a photosensitive layer containing an inorganic photoconductive substance such as selenium, zinc oxide, or cadmium sulfide has been widely used.

On the other hand, the use of various organic photoconductive substances as materials for photosensitive layers of electrophotographic photoreceptors has been actively developed and researched in recent years.

For example, in Japanese Patent Publication No. 50-10496, poly-N-
Vinyl carbazole and 2.4.7, -trinitro-9-
An organic photoreceptor having a photosensitive layer containing fluorenone is described. However, this photoreceptor is not always satisfactory in terms of sensitivity and durability. In order to improve these drawbacks, attempts have been made to develop organic photoreceptors with high sensitivity and durability by assigning the carrier generation function and carrier transport function to different substances in the photosensitive layer. ing.

In such so-called function-separated type electrophotographic photoreceptors, it is possible to select substances that exhibit each function from a wide range, so it is relatively easy to create an electrophotographic photoreceptor with any desired characteristics. It is possible to make one.

Many substances have been proposed as carrier-generating substances that are effective for such functionally separated electrophotographic photoreceptors.

Examples of using inorganic substances include, for example, Japanese Patent Publication No. 43-16
As described in the '198 publication, there is amorphous selenium, which is combined with an organic carrier transport material.

In addition, many electrophotographic photoreceptors using organic dyes or organic pigments as carrier-generating substances have been proposed. Publication No. 55-22834, Japanese Patent Application Laid-open No. 79632-1982, Japanese Patent Application Publication No. 1987-11
This is already known from Publication No. 6040 and the like.

By the way, the conventional photoreceptor using the organic photoconductive substance is usually used for negative charging.

The reason for this is that when negatively charged, the mobility of holes among carriers is high, which is advantageous in terms of photosensitivity and the like. However, it has been found that using such negative charging causes the following problems. That is, there is a problem in that ozone is likely to be generated in the atmosphere during negative charging by the charger, worsening the environmental conditions. Still another problem is that positive polarity toner is required for development of a negatively charged photoreceptor, but positive polarity toner is difficult to manufacture in view of the triboelectrification series with respect to ferromagnetic carrier particles.

Therefore, it has been proposed to use a photoreceptor using an organic leading conductive material with a positive belt. For example, when forming a photoreceptor by laminating a carrier transport layer on a carrier generation layer,
In order to efficiently cancel the positive charge on the surface of the photoreceptor, a substance with a high electron transport ability, such as trinitrofluorenone, is used in the carrier transport layer, but this substance is carcinogenic and extremely unsuitable from a pollution standpoint. .

Furthermore, as a positive charging photoreceptor, U.S. Patent No. 361541
Specification No. 4 discloses a material containing a devirylium salt (carrier generating substance) so as to form a eutectic complex with polycarbonate (binder resin). However, this known photoreceptor has the drawbacks of a large memory phenomenon and a tendency to generate ghosts. Also, U.S. Patent No. 335
No. 7989 also discloses a photoreceptor containing phthalocyanine, but phthalocyanine has the disadvantage that the characteristics change depending on the crystal type and that the crystal type must be strictly controlled. In addition, it has a large memory phenomenon and low sensitivity to short wavelengths, so it is considered to be unsuitable for copying machines whose light source is visible light including the short wavelengths.

As described above, various attempts have been made to obtain positively charging photoreceptors, but all of them have many problems that need to be improved in terms of photosensitivity, memory, pollution, etc.

[Problem that the invention seeks to solve]

Therefore, the photosensitive layer has a laminated structure in which the upper layer (surface layer) is a carrier-generating layer containing a carrier-generating substance that generates holes and electrons when irradiated with light, and the lower layer is a carrier-transporting layer containing a carrier-transporting substance having a hole-transporting function. It is conceivable to use the photoreceptor for positive charging. Furthermore,
It is considered that a photoreceptor having a single-layered photosensitive layer containing the carrier-generating substance and the carrier-transporting substance can also be used for positive charging. In addition, in such a photoreceptor that is used for positive charging, if a carrier generating substance having, for example, an electron-withdrawing group is used in the structure, the movement of electrons to cancel the positive charge on the surface of the photoreceptor will be accelerated. , it is thought that high sensitivity characteristics can be obtained.

However, since each of the positive charging photoreceptors has a layer containing a carrier-generating substance formed as a surface layer, the carrier-generating substance is sensitive to external effects such as light irradiation, corona discharge, humidity, and especially mechanical friction. ni exists near the back surface layer, resulting in deterioration of electrophotographic performance and deterioration of image quality during storage of the photoreceptor and in the process of image formation.

In a negative charging photoreceptor having a conventional carrier transport layer as a surface layer, the effects of the various locus effects described above are extremely small.
Rather, the carrier transport layer has the function of protecting the underlying carrier generation layer.

On the other hand, in the case of a positively charging photoreceptor, the surface layer, which contains a carrier-generating substance, is subject to mechanical abrasion and damage due to external effects, especially development and cleaning, resulting in white spots and
Image defects such as white streaks and other surface potential1. sensitivity, memory,
Deterioration of electrophotographic performance, such as residual potential, begins to occur.

Therefore, it is conceivable to provide a thin protective layer made of an insulating and transparent resin to make the layer containing the carrier-generating substance M strong, but the gear which is generated during light irradiation is blocked by the protective layer and becomes photoconductive. There is a problem with the loss of sexuality.

[Means for solving problems]

(Objective of the Invention) The object of the present invention is to provide a protective layer on the surface layer of the photoreceptor that does not affect the electrophotographic characteristics inherent to the photoreceptor, thereby preventing light irradiation, corona discharge, etc. The object of the present invention is to improve the printing durability of a positive charging photoreceptor by suppressing the effects of premature change and especially harmful external effects such as mechanical wear and damage.

(Structure of the Invention) The above-mentioned object has a protective layer containing an electron-accepting substance and an electron-donating substance as substances contributing to the transport of carriers, and the binder of the protective layer is hardened by light or heat. This is achieved by using a positive charging photoreceptor whose main component is a resin.

In the photoreceptor of the present invention, a photosensitive layer having a single layer structure containing a carrier generating substance, a gear transport substance, and optionally a binder resin, or a gear carrier transport layer containing a carrier transport substance and optionally a binder resin as the lower layer. , an electron-accepting substance and an electron-donating substance are placed on a photosensitive layer having a laminated structure including a carrier-generating substance on the carrier-transporting layer and, if necessary, a carrier-generating layer containing a carrier-transporting substance and a binder resin as an upper layer (surface layer). forming a protective layer containing
Moreover, by using a thermosetting resin as the binder of the protective layer, the mechanical strength of the surface of the photoreceptor is improved and printing durability is improved.

In the photoreceptor configured as described above, when the layer containing a carrier-generating substance is irradiated with light and hole-supported electrons are generated, the holes quickly move to the substrate side via the carrier transport layer, and the electrons are is a CT complex (Charge Transfer
complex), it quickly moves through the protective layer and cancels out the positive charges on the surface. In this way, even a photoreceptor coated with a protective layer exhibits high sensitivity characteristics.

Examples of electron-accepting substances used in the protective layer of the photoreceptor of the present invention include succinic anhydride, maleic anhydride, dibromaleic anhydride, phthalic anhydride, tetrachlorophthalic anhydride, tetrabromophthalic anhydride, 3-nitro Phthalic anhydride, 4-nitrophthalic anhydride, pyromellitic anhydride, mellitic anhydride, tetracyanoethylene, tetraanoquinotumethane, 0-dinitrobenzene, m-dinitrobenzene, 1,3,5. - Trinitrobenzene, paranitrobenzonitrile, picryl chloride, quinone chlorimide, chloranil, brumanil, 2-medylnaphthoquinone, dichlorodine anovaranhenzoquinone, anthraquinone, nonitroanthraquinone, trinitrofluorenone, 9-fluorenonedene [dicyano methylenemalonodinitrile], polynitro-9-fluorenonedene[
dianomethylenemalonodinitrile], picric acid, 〇-nitrobenzoic acid, p-nitrobenzoic acid, 3.5-nitrobenzoic acid, pentafluorobenzoic acid, 5-nitrosalicylic acid, 3.5-dini)・Examples include rosalicylic acid and phthalic acid.

As an electron-accepting substance suitable for forming a CT complex with an electron-donating substance to be described later, it is better to have a large electron affinity EA, preferably in the range of 0.3 eV≦EA≦1.8 eV.

Next, there are no particular restrictions on the electron-donating substance, but for example, the 1- to 3-treated amines described in JP-A No. 52-55643, or the P-type carrier transporting substance used in conventional functionally separated photoreceptors. Both are used.

However, the carrier transporting substances described below useful in the photosensitive layer of the photoreceptor of the present invention are also considered to be extremely useful as the electron-donating substances. Such electron-donating substances are exemplified compound group CIX.
) and (X) are the styryl compounds, the hydrazone compounds are the exemplified compound groups (XI) to (XV), the pyrazoline compounds are the exemplified compound groups (XV[), the exemplified compound groups [X\I] In addition to these, polyvinylcarbazole or its derivatives are also preferably used. The amount of the electron-accepting substance contained in the protective layer is 0.1 to 50% by weight; if it is less than 0.1% by weight, the photosensitivity will be insufficient, and if it exceeds 50% by weight, the solvent solubility will be poor. . The amount of the electron-donating substance contained in the protective layer is 20 to 200% by weight, and if it is less than 20% by weight, the photosensitivity will be poor, and if it is more than 200% by weight, the solvent solubility will be poor.

Next, the protective layer containing the electron-accepting substance and the electron-donating substance as a binder has a volume resistivity of 10 8 Ω·cm or more, preferably 10 10 Ω·cm or more, more preferably 10
A transparent resin with a resistance of 3Ω・cm or more should be used. In addition, the binder is hardened by light or heat at least 50%.
It is assumed that the content is 1% or more by weight.

Examples of such resins that harden with light or heat include thermosetting acrylic resins, silicone resins, epoxy resins, urethane resins, urea resins, phenol resins, polyester resins, alkyd resins, melamine resins, photocurable/cinnamic acid resins, etc. Alternatively, copolymerization of these resins includes cocondensation resins, and all of the photo-curable or thermosetting resins used in electrophotographic materials can be used. If necessary, the protective layer may contain less than 50% by weight of a thermoplastic resin for the purpose of improving processability and physical properties (preventing cracks, imparting flexibility, etc.). Examples of such thermoplastic resins include polypropylene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, epoxy resin, butyral resin,
Polycarbonate resins, silicone resins, or copolymer resins thereof, such as hinyl chloride-vinyl acetate copolymer resins, vinyl chloride-vinyl acetate-maleic anhydride copolymer resins, polymeric organic semiconductors such as poly-N-vinylcarbazole, All of the thermoplastic resins available in the low electrophotographic material are utilized.

In addition to the electron-accepting substance, the protective layer may contain an ultraviolet absorber or the like for the purpose of protecting the carrier generation properties, if necessary, and is dissolved in a solvent together with the binder, for example, by dip coating, spray coating, blade coating, etc. It is applied and dried by coating, roll coating, etc. to a thickness of 2 μm or less, preferably 1 μm.
It is formed to a layer thickness of μm or less.

Note that the film thickness after drying is a thin film that is below the measurement limit, and a considerable reinforcing effect is exerted just by fixing the particles of the carrier-generating substance.

The resistance of the binder in the protective layer is measured as follows.

When a sample is placed in a measurement cell with a cross-sectional area of 1 cm2 (F cm') to a depth of 0.03 to 0.08 cm (h cm), a load of IKg is applied from the top, and the applied voltage (V volts) is varied. The current value (i ampere) is measured and calculated using the following formula.

Next, as the carrier generating substance suitable for the present invention, any of inorganic pigments and organic dyes can be used as long as it absorbs visible light and generates free carriers. In addition to inorganic pigments such as amorphous selenium, trigonal selenium, selenium-arsenic alloy, selenium-tellurium alloy, cadmium sulfide, cadmium selenide, cadmium selenide sulfide, mercury sulfide, lead oxide, lead sulfide, the following representative examples Organic pigments such as those shown may also be used.

(1) Azo pigments such as monoazo pigments, polyazo pigments, metal complex azo pigments, pyrazolone azo pigments, stilbene azo pigments, and thiazole azo pigments.

(2) Perylene pigments such as perylene anhydride and perylene imide.

(3) anthraquinone derivatives, anthanthrone derivatives, dibenzpyrenequinone derivatives, pyrantrone derivatives,
Anthraquinone group or polycyclic quinone pigments such as violanthrone derivatives and isoviolanthrone derivatives (I) Indigoid pigments such as ingo derivatives and thioindigo derivatives (5) Phthalonanine pigments such as metal phthalocyanine and metal-free phthalonanine (6) Diphenylmethane type pigments pigments, carbonium pigments such as triphenylmethane pigments, xanthine pigments and acridine pigments (7) quinone imine pigments such as azine pigments, oxazine pigments and thiazine pigments (8) methine pigments such as anine pigments and azomethine pigments (9) quinoline Pigments (10) Nitro pigments (11) Nitroso pigments (12) Benzoquinone and naphthoquinone pigments (13)
Naphthalimide pigments (14) Perinone pigments such as hishenzimidazole derivatives, but preferably azo or polycyclic quinone pigments with an electron-withdrawing group, in the form of granules with an average hourly diameter of 2 μm or less, especially 1 μm or less It is preferable to include a fraction in the photosensitive layer.

In this case, the electrophotographic properties of the photoreceptor, such as photosensitivity, memory phenomenon, residual potential, etc., become better.

In addition, the azo pigment has a higher electron transfer rate in the photosensitive layer when the surface of the photosensitive layer is negatively charged than when it is positively charged (
In other words, since the photosensitivity is high when negatively charged, the electrons generated during light irradiation quickly cancel out the positive charges on the surface of the photosensitive layer, and exhibit high photosensitivity characteristics.

In other words, when used in the surface layer of a positively charging photoreceptor, it is extremely advantageous in terms of photosensitivity.

Examples of azo pigments suitable for the present invention include those shown in the following exemplary compound groups [I] to (V).

Exemplified compound group [I]: Exemplified compound group (n) / Exemplified compound group [■]: Exemplified compound [■]: Exemplified compound (V) / The following exemplified compound group (Vl) as a carrier-generating substance
Polycyclic quinone pigments shown in ~[■] are frequently used.

Compound vIR〒 r ■〕 : Exemplary compound group [■ Next Carrier transport substances that can be used in the present invention are not particularly limited, but include, for example, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, and thiadiazole. Derivatives, l-lyazole derivatives, imidazole derivatives, imidasilone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazone compounds, pyrazoline derivatives, oxazole derivatives, benzothiazole derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, They may be phenazine derivatives, aminostilchene derivatives, poly-N-vinylcarbazole, poly-1-vinylpyrene, poly-9-vinylanthracene, and the like.

However, it is preferable to use a carrier transporting substance that not only has an excellent ability to transport the light-irradiating generating pole to the support side but also is suitable for combination with the carrier-generating substance, and such carrier-transporting substances include, for example, the following exemplified compound group CIX). Alternatively, a methyl compound represented by [X] is used.

Exemplary compound 1r# CIX).

Exemplary compound group (X) Also, the following exemplary compound groups [Kari] to [Kari] as carrier transport substances
A hydrazone compound represented by X] can also be used.

Exemplified compound group [■] Exemplified compound group (XI): Exemplified compound group (XIV)/Exemplified compound group (XV): Pyrazoline compounds shown in the following exemplary compound CXVI) can also be used as carrier transport substances.

Exemplified compound group (XVI): ゛ Also, the following exemplary compound group [X■
] It is also possible to use amine derivatives represented by the following.

As described above, the photoreceptor of the present invention has a single-layer photosensitive layer on a support containing a carrier-generating substance, a carrier-transporting substance, and optionally a binder resin, or a photosensitive layer containing a carrier-generating substance and optionally a carrier-transporting substance and a binder resin. A photosensitive layer is provided in a laminated structure, with a carrier generation layer containing the carrier-generating layer as an upper layer, a carrier-transporting layer containing a carrier-transporting substance and, if necessary, a binder resin, as a lower layer, and a protective layer further provided thereon.

Examples of binder trees that can be used in the photosensitive layer of such photoreceptors include polystyrene, polyethylene, polypropylene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, polyurethane resin, Phenolic resin, polyester resin, alkyd resin, polycarbonate resin,
Addition polymer resins such as silicone resins and melamine resins, polyaddition resins, polycondensation resins, and copolymer resins containing two or more repeating units of these resins, such as vinyl chloride-vinyl acetate copolymers Examples include insulating resins such as polymer resins and vinyl chloride-vinyl acetate-maleic anhydride copolymer resins, as well as polymeric organic semiconductors such as poly-N-vinylcarbazole.

Further, in the photoreceptor of the present invention, organic amines can be added to the photosensitive layer for the purpose of improving the carrier generation function of the gear generation substance, and it is particularly preferable to add a 2-handling amine.

Such secondary amines include, for example, di-methylamine, diethylamine, di-propylamine, di-isopropylamine, di-n-butylamine, di-isobutylamine, di-n-amylamine, di-isoamylamine, di-n-
Hexylamine, di-isohexylamine, di-n-pentylamine, di-isopentylamine, di-n-octylamine, di-isooctylamine, non-n-nonylamine, di-isononylamine, di-n-decylamine, di- Examples include isodecylamine, di-n monodecylamine, di-isomonodecylamine, di-n dodecylamine, and di-isododecylamine.

The amount of the secondary amine to be added is preferably 1 times or less, preferably -0.2 times to 0.005 times the amount of the carrier generating substance, based on the amount of the carrier generating substance.

Next, the conductive support supporting the photosensitive layer is a metal plate made of aluminum, nickel, etc., a metal drum or metal foil, a plastic film deposited with aluminum, tin oxide, indium oxide, etc., or paper coated with a conductive substance. , a film or drum of plastic or the like can be used.

The layer structure of the photosensitive layer of the photoreceptor of the present invention has a single layer structure and a laminated structure as described above. Since it has a property of promoting properties, it is also possible to increase m of the carrier-generating substance relative to the binder resin in the layer containing the carrier-generating substance more than before. Therefore, the range of improvement in electrophotographic properties such as sensitivity, memory, residual potential, etc. of the photoreceptor is expanded accordingly.

When the photoreceptor of the present invention has a single layer structure, the ratio of the carrier generating substance contained in the binder resin is 100% of the binder resin.
20 to 200 parts by weight, preferably 25 to 200 parts by weight
The amount is 100 parts by weight.

If the content of the carrier-generating substance is less than this, the photosensitivity will be low and the residual potential will increase, and if it is more than this, the dark decay and acceptance potential will decrease.

Next, the ratio of the carrier transport substance to the binder resin is 20 to 100 parts by weight of the binder resin.
The amount is 200 parts by weight, preferably 30 to 150 parts by weight.

If the content of the carrier transport substance is less than this, the photosensitivity will be poor and the residual potential will tend to be high, and if it is more than this, the solvent solubility will be poor.

The weight ratio of the carrier transporting substance to the carrier generating substance in the single-layer photosensitive layer is preferably 1:3 to 1:2.

Next, in the case of the above-mentioned laminated structure, the carrier-generating material is 20 to 20% per 100 parts by weight of the binder resin in the carrier-generating layer.
0 parts by weight, preferably 25 to 100 parts by weight, and the carrier transport substance contains 20 to 200 parts by weight, preferably 30 to 100 parts by weight.
The amount is 150 parts by weight. If the amount of the carrier generating substance is less than this, the photosensitivity will be low and the residual potential will increase, and if it is more than this, the dark decay will increase and the acceptance potential will decrease. Furthermore, if the amount of the carrier transport substance is less than this, the photosensitivity will decrease and the residual potential will increase, and if the amount is more than this, the solvent solubility will deteriorate.

Next, in the case of the laminated structure, the carrier transport material is 20 to 200 per 1001 parts of the binder resin in the carrier transport layer.
Parts by weight, preferably 30 to 150 parts by weight.

If the content of the gear transport substance is less than this, the photosensitivity will be poor and the residual potential will tend to be high, and if it is more than this, the solvent solubility will be poor.

The positive charging photoreceptor of the present invention is constructed as shown in FIGS. 1 to 3, for example.

FIG. 1 shows a photosensitive layer 4 having a single-layer structure with a film thickness of 2 μm to 20 μm in which a granular carrier-generating material 6 made of the azo pigment is dispersed in a layer containing the carrier transporting material 7a and a binder resin. A protective layer 8 is provided directly or via an intermediate layer (not shown) on the support l, and further contains an electron-accepting substance, an electron-donating substance, and a thermosetting resin thereon.
This shows a configuration with .

Further, FIG. 2 shows a carrier transport layer 3 with a thickness of 5 μm to 50 μm containing a carrier transport substance 7b and a binder resin, and a film with a thickness of 0.05 μm in which the granular carrier generating substance 6 is dispersed in the layer containing the binder resin. A photosensitive layer 4 having a laminated structure consisting of a carrier generation layer 2 of ~10 μm is provided on a conductive support, and a protective layer 8 containing an electron-accepting substance, an electron-donating substance, and a thermosetting resin is further provided thereon. The installed configuration is shown.

FIG. 3 shows that the carrier transport substance 7a is also contained in the carrier generation layer 2 of FIG. 2, and that an intermediate layer 5 with a thickness of 0.005 μm to 5 μm is provided between the photosensitive layer 4 and the support 1. This point differs from the layer structure shown in FIG.

Here, as a method for manufacturing such a photoreceptor, for example, a carrier generating substance 6 is dispersed in the form of fine particles of o, oi-1,0 μm in a dispersion medium, and a binder resin and a carrier transporting substance 7a are dispersed.
A coating solution is prepared by mixing and dispersing, for example, by ultrasonic dispersion, and coated onto the conductive support l via an intermediate layer 5 if necessary, by a coating method such as dip, spray, blade, or roll. The photosensitive layer 4 is dried to obtain a photosensitive layer 4, and then a thin layer of a solution containing an electron accepting substance, an electron donating substance and a thermosetting binder resin is applied and dried to form a protective layer 8. A photoreceptor having a photosensitive layer having a single layer structure as shown in FIG. 1 is obtained.

Also, for example, a binder resin and a carrier transport substance 7 may be present in a solvent.
A solution in which b is dissolved is coated on a conductive support via an intermediate layer 5 if necessary and dried to form a carrier transport layer 3, and on top of this, for example, the photosensitive layer 4 of FIG. 1 is applied as a carrier generation layer. 2
A protective layer 8 similar to that shown in FIG. 1 is further formed to obtain a photoreceptor having a photosensitive layer having the laminated structure shown in FIGS. 2 and 3.

Examples of the solvent used to form each layer include N,
N-dimethylformamide, benzene, toluene, xylene, monochlorobenzene, -■.

Examples include 2-dichloroethane, dichloromethane, 1,1,2-trichloroethane, tetrahydrofuran, methyl ethyl ketone, ethyl acetate, and butyl acetate.

The intermediate layer 5 functions as an adhesive layer or a barrier layer, and includes, in addition to the binder resin, polyvinyl alcohol, ethyl cellulose, carboxymethyl cellulose, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate, etc. Maleic anhydride copolymer, casein, starch, etc. are used.

〔Example〕

The present invention will be explained below with reference to Examples, but the embodiments of the present invention are not limited thereby.

[Example 1] A conductive support made of polyester laminated with aluminum foil was coated with an approximately 0-thick film made of vinyl chloride-vinyl acetate-maleic anhydride copolymer ([S-LEC MF-IOJ, manufactured by Sekisui Chemical Co., Ltd.]). An intermediate layer of .05 μm was formed. Next, 30 parts of the bisazo carrier-generating substance shown in Compound Example (IV-7) and Ichikoki Compound Example (IX
-43) 75 parts by weight of the carrier transport substance and binder resin polycarbonate (Panlite-1250J
100 parts by weight (manufactured by Teijin Kasei Co., Ltd.) in 1500 parts by weight of a 1,2-dichloroethane/no-isobutylamine mixed solvent containing an amine such that the amount is 0.02 mol per 1 mol of the carrier generating substance +: IjO Then, the mixture was mixed and dispersed in a ball mill for 12 hours.

The obtained dispersion was applied onto the intermediate layer and dried to form a layer of 12 μm.
A thick single-layer photosensitive layer was obtained. Next, dicyanodichlorobenzoquinone 0 is added to this photosensitive layer as an electron-accepting substance.
．． 42 parts by weight of polyvinylcarbazole (PVK) as an electron-donating substance, 0.60 parts by weight of thermosetting polyester resin as a binder resin, and 1.0 parts by weight of the polycarbonate resin, 100 parts by weight of 1.2-dichloroethane as a solvent. A coating liquid obtained by dissolving the coating solution in the overlapping area was applied in a thin layer by a spray coating method and dried to form a protective layer with a thickness of 100 mm, thereby obtaining a photoreceptor of the present invention.

(Examples 2 to 10) Nine types of photoreceptors of the present invention were obtained by changing the types of electron-accepting substances and electron-donating substances in the protective layer as shown in the attached table, and making the other conditions the same as in Example 1. .

(Comparative Examples 1 to 5) By removing the protective layer, or by removing the electron-accepting substance and the electron-donating substance in the protective layer, or by excluding only the electron-donating substance,
A comparative photoreceptor of type 1 was obtained in the same manner as in Example 1, except that the type of electron-accepting substance was changed as shown in the attached table.

(Example 11) Vinyl chloride-vinyl acetate-maleic anhydride copolymer [S-LEC M
P-10j (manufactured by Tsukisui Kagaku Kogyo Co., Ltd.) with a thickness of 0.
An intermediate layer of 0.05 μm was provided.

Next, 50 parts by weight of the polycyclic quinone carrier generating substance shown in the above compound example (Vl-4) and the above compound example (IX-7) were added.
5) 75 parts by weight of the carrier transport substance and polycarbonate ("Panlite LL250J") as a binder resin.
100 parts by weight (manufactured by Teijin Kasei Co., Ltd.) were added to 2500 parts by weight of a mixed solvent of dichloromethane/trichloroethane, and mixed and dispersed in a ball mill for 12 hours.

The obtained dispersion was applied onto the intermediate layer and dried to a thickness of 13 μm.
A thick single-layer photosensitive layer was obtained. Next, on this photosensitive layer, cyanodichlorobenzoquinone was added as an electron-accepting substance.
, 1.20 parts by weight of the above-mentioned exemplary compound (IX-75) as an electron donating substance, and 1.55 parts by weight of thermosetting acrylic-melamine-epoxy (1:1:I) resin as a solvent. A coating solution obtained by dissolving monochlorobenzene in 100 parts by weight of 1.1.2-trichloroethane was coated in a thin layer by a spray coating method and dried to form a protective layer with a thickness of 100 mm. I got it.

(Examples 12 to 19) Eight types of photoreceptors of the present invention were obtained in the same manner as in Example 11, except that the types of electron-accepting substances and electron-donating substances in the protective layer were changed as shown in the attached table.

(Comparative Examples 6 to 9) The electron-accepting substance and the electron-donating substance in the protective layer were removed, or only the electron-accepting substance was removed, and the type of the electron-accepting substance was changed as shown in the attached table. Four types of comparative photoreceptors were obtained in the same manner as in Example 1.

The thus obtained photoreceptor was subjected to electrostatic test N1rSP-428.
The following characteristic tests were conducted by installing the device in a ``Kawaguchi Denki Seisakusho'' (newly manufactured by Kawaguchi Denki Seisaku). That is, a voltage of +6 KV is applied to the charger to charge the photosensitive layer by corona discharge for 5 seconds, and then the photosensitive layer is left for 5 seconds (the potential at this time is called the initial potential), and then the illuminance on the surface of the photosensitive layer is 14 lux ( In the case of Examples 1 to 10 and Comparative Examples 1 to 5) or 35 Lux (Example 11)
19 and Comparative Examples 6 to 9), the exposure required to attenuate the initial potential from +600 volts to +100 volts and +50 volts by irradiating light from a tungsten lamp ) was measured.

In addition, the residual potential V
r+volts were measured. Furthermore, the residual potential Vrs was also measured when the above steps were repeated five times (however, the residual potential was erased at the end of each of the first to fourth steps). Furthermore, the mechanical strength of the surface of each photoreceptor was measured under the following conditions using a modified U-Bix 2500tvfR (manufactured by Konishiroku Photo Industry Co., Ltd.), and the obtained results were evaluated using the "○" and "x" system.

The above measurement results are shown in the attached table.

The conditions for measuring mechanical strength are as follows.

U-Bix 2500M R modification (using geometry, after current 1'Q L under reverse bias, with PE blade (Luminar manufactured by Toshisha)) Continuous 10,0 with a load of 00gf/cm
The cleaning process of 00 cycles was repeated to cause forced abrasion, and the resulting degree of abrasion on the surface of the photoreceptor and the change in image quality when an image was formed on the photoreceptor were visually judged. The photoreceptors of the present invention all have excellent electrophotographic properties and mechanical strength, whereas the comparative photoreceptors have drawbacks such as excessive residual potential and weak 11A strength. I understand that.

(Example 20) Vinyl chloride-vinyl acetate-
Maleic anhydride copolymer “S-LEC MF-10j
(manufactured by Tsukisui Kagaku Co., Ltd.) with a thickness of about 0.05 μm was formed. Next, 9.9 parts by weight of the carrier transport substance shown in the above compound example (IX-54) and 32 parts by weight of binder resin polycarbonate ([Panlite-1250J manufactured by Teijin Kasei Co., Ltd.) were added to 100 parts by weight of 1,2-dichlorocholethane. A solution obtained by mixing and dissolving in a ball mill for 12 hours was applied onto the intermediate layer and dried to obtain a carrier transport layer with a thickness of 13 μm.

Next, 30 parts by weight of the carrier-generating substance represented by Exemplified Compound (IV-7), 75 parts by weight of the carrier-transporting substance represented by Exemplary Compound (IX-54), 100 parts by weight of the polycarbonate binder resin, and 1 part by weight of the carrier-generating substance. 0.02 mol of di-isobutylamine per mole of 1.2-
In addition to 1500 parts by weight of dichloroethane, 1
A dispersion obtained by dispersing for 2 hours was applied onto the carrier transport layer and dried, and a carrier generation layer having a thickness of 5 μm was laminated to form a photosensitive layer having a laminated structure.

Next, 0.32 parts by weight of 2-methylnaphthoquinone as an electron-accepting substance and P as an electron-donating substance were placed on the photosensitive layer.
V. 828'' mixture of three types of resin solutions manufactured by Yuka Shell Epoxy Co., Ltd.) 1.60 parts by weight (solid content) and 1 part xylene solvent
A coating solution was prepared by dissolving 0.00 parts by weight, and this was coated by a spray coating method and dried to form a protective layer with a thickness of 0.5 μm to obtain a photoreceptor of the present invention.

Using this photoreceptor, electrophotographic performance and mechanical strength were measured using the same measuring method as in Example 1, and it was found that it had excellent characteristics similar to the photoreceptor of Example 1.

〔Effect of the invention〕

As is clear from the above description, according to the photoreceptor of the present invention,
The photoreceptor surface has high mechanical strength, is highly durable, has high sensitivity characteristics for positive charging, and has excellent residual potential and other electrophotographic performance. .

[Brief explanation of drawings]

1 to 3 are cross-sectional views of the positively charging photoreceptor of the present invention. 1. Support body 2. ...carrier generation layer 3, ...carrier transport layer 4 ...photosensitive layer 5, ...intermediate layer 6 ...carrier generation material 7, ...gear transport material 8, ...protective layer

Claims (7)

[Claims] (1) having a protective layer containing an electron-accepting substance and an electron-donating substance as substances contributing to the transport of charge carriers;
1. A photoreceptor for positive charging, characterized in that the binder of the protective layer contains a resin that is cured by light or heat as a main component. (2) The electron-accepting substance is present in the protective layer at 0.1 to 5
The positive charging photoreceptor according to claim 1, which contains 0% by weight. (3) The electron-donating substance is present in the protective layer at a concentration of 20 to 20%.
Positive charging photoreceptor according to claim 1 containing 0% by weight (4) Claim 1, wherein the protective layer is provided on a photosensitive layer containing a carrier-generating substance and a carrier-transporting substance.
Positive charging photoreceptor as described in . (5) The photoreceptor for positive charging according to claim 4, wherein the carrier generating substance comprises an azo pigment or a polycyclic quinone pigment. (6) The photoreceptor for positive charging according to claim 4 or 5, wherein the carrier generating substance comprises an azo pigment or a polycyclic quinone pigment having an electron-withdrawing group. (7) The photoreceptor for positive charging according to claim 4, wherein the carrier transport substance is a styryl compound, a hydrazone compound, a pyrazoline compound, or an amine derivative as described in the main text.